What was the BFG's reaction to catching the trogglehumper?

In Chapter Twelve, Dream-Catching, Sophie and the BFG have finally reached Dream Country, where the BFG immediately pauses to set down his suitcase while telling Sophie they must be very quiet. Soon after, the BFG swings his net, catches a dream, and places it in a glass jar, declaring that he has caught an excellent dream.... a “golden phizzwizzard.” He the catches another dream... a nightmare that he calls a “trogglehumper.” The BFG becomes so upset by the trogglehumper that he decides it is time to return home, and he races there as quickly as his feet will take him.